A diversity of patient handling and assisting problems may be found in any healthcare environment that deals with physically disabled persons. For this reason, single devices capable of performing a variety of assistive functions are of obvious value both to care facilities and to mobility impaired individuals in private care situations.
Several devices already exist that attempt to provide such multiple functionality. Examples include the devices disclosed by Wilson in U.S. Pat. No. 6,092,247, Su et al. in U.S. Pat. No. 7,392,554, Aubert in U.S. Pat. No. 4,704,749, and Dunn in U.S. Pat. No. 6,389,619. These devices aim to raise a disabled person in the seated, standing, or semi-standing postures for transfer between various objects, such as between a wheelchair and bed or commode, as well as to assist the person in standing and walking.
Most of these devices, including those mentioned above, lift the person along a line or arc to which little or no modification can be made, resulting in undesirable characteristics or limitations in the way the device performs one or the other of the intended functions.
For example, the device discussed in the Aubert patent lifts along a vertical path and thus should function well as a means to raise and reposition a person while that person is held in a seated posture. However, a standing motion requires that the person's torso be moved forward as well as upward to place the body in a balanced upright position where the center of gravity is above the feet. While a person's torso could be moved forward with such a device by having the caregiver or a wheel drive system roll the device forward while the device lifts the person vertically, such rolling requires extra effort on the part of the caregiver. In addition, knee and shin abutments are typically incorporated in standing motion devices to stabilize the legs and prevent the lower body from swinging forward disadvantageously during the standing motion. However, even if the Aubert patent were to include such abutments, the rolling of the device to move the torso forward would move the abutments away from the person, negatively affecting the lifting-to-standing action.
Other devices, such as those discussed by Wilson in U.S. Pat. No. 6,092,247, Su et al. in U.S. Pat. No. 7,392,554, and Dunn in U.S. Pat. No. 6,389,619, lift along a fixed arc or line that moves forward as well as up and likely serve well as standing aids. However, such devices have limitations as transfer devices because any vertical movement of the person is accompanied by substantial horizontal movement, especially along the upper region of the fixed arc. This horizontal movement forces the caregiver to constantly monitor and adjust the position of the device as the person is lowered, to prevent the person from being placed too far forward or rearward on the object onto which he or she is being seated. Similarly, the added horizontal movement also makes transfers between objects of significantly different heights awkward or difficult as should be appreciated by persons with knowledge of invalid care environments who must navigate persons between objects such as commodes and therapy tables, which are generally lower in height and changing tables, hospital beds and powered wheelchairs which are usually considerably higher.